Poly(phthalaldehyde) (pPHA) and copolymers with aliphatic aldehydes were investigated as dry-develop, positive-tone photoresist. Exposure of the films loaded with a photoacid generator to 248 nm radiation creates an acid that depolymerizes the polymer into volatile monomers, allowing the development of features by vaporization rather than solution-based processes. By controlling the acid content, the vaporization rate of the reaction products, and the degree of liquid formation of the decomposed polymer, control of spatial resolution and the quality of polyaldehyde dry-develop photoresist was achieved. Heat, vacuum, and forced convection were evaluated as development techniques in determining the resist sensitivity, contrast, and resolution. Forced convection of heated nitrogen was the most controllable development method for pPHA films. Five-micron lines and spaces were printed. Poly(aldehyde) copolymer resins had slightly lower spatial resolution but were able to be developed faster due to higher vapor pressure of the depolymerized monomers. Cold photo-exposures and development were used to prevent detrimental liquid formation of the decomposed copolymers. In addition to exploring new dry-development methods that have not been tested before, these findings offer insights into designing better material systems and optimizing processes for dry-develop photoresists.

A method for creating pH maps in microchannels containing liquid/liquid and liquid/gas phases comprised of water and CO2 is demonstrated. It is based on a glass slide coated with nanoparticles exhibiting metal-enhanced fluorescence. The time resolution is better than 500 ms, limited by the fluidic control. This work opens the way for new in situ measurements of physical dissolution and chemical reactions in dynamic CO2 gas-liquid systems.

Understanding spatial and temporal neuronal activities is crucial for finding the cure for brain related ailments and advancement of our knowledge about the brain itself. This paper discusses our recent finding of the patternable rough textured gold microwire for neurochemical sensing. We have successfully fabricated the ∼5 µm wide and ∼ 60 nm thick gold microwires based electrochemical sensor. We produced these microwires along the edge of lithographically patterned nickel thin film. A nickel thin film edge was shadowed by the photoresist overhang during electrochemical growth only to allow gold deposition along the edges. Our electrochemical growth conditions yielded very rough textured sensor. Rough textured biosensors are highly desirable for increasing surface/volume ratio for efficient electrochemical sensing. These rough-textured microwires were transformed into the functional neurochemical sensor to detect dopamine. Our voltammetry and chronoamperometry studies on rough textured microwires based sensor confirmed the successful detection of dopamine.

We report the preparation of nanomasks for silicon plasma etching, which is not based on full top-down approaches such as conventional lithographic process. We used laterally phase separated polymers thin films (30 to 100 nm thick) obtained from immiscible polymer blends of poly(styrene) PS and poly(lactide) PLA, PS being the major component, spin-coated onto silicon substrates. Despite the high incompatibility of the two polymers, submicronic domains were obtained in the film. The selective extraction of the minor component (PLA) led to the formation of a perforated layer of PS at the top of the silicon substrate, and was used as a mask for the selective etching of the silicon. For that purpose, we used a cryogenic etching process where the silicon substrate was cooled at a cryogenic temperature (∼ -120°C) and exposed to a monocyclic SF6/O2 plasma. It was possible to etch anisotropic profiles with vertical sidewalls and minimal defects. Etched feature with an aspect ratio of 7 were obtained in these conditions. We determined that the selectivity of etching (Si/PS) was 11:1, with a silicon etching rate of 0.8 µm/min. The selectivity of these masks was further increased when using the inorganic replicas of the polymer template (50:1) or with chemical modifications of the PS by RuO4 (80:1), allowing for increased aspect ratio etched features (up to 20 in the latter case). Optimized etching processes (such as STiGer process) were also used in order to improve the reproducibility and robustness of the method.

This paper introduces a fabrication method to achieve sub-15 nm line-and-space (L/S) patterns by combining grapho- and chemo-epitaxy using poly(styrene-block-methyl methacrylate) copolymer (PS-b-PMMA). The fabrication method is simple, since it eliminates photoresist stripping and also does not require any special materials to form pinning patterns. In this process, the ridges formed on spin-on-glass (SOG) surface work as physical guides and the photoresists on them are utilized as a pinning layer. Fine PS-b-PMMA L/S patterns were obtained in sufficient critical dimension (CD) range of the guide patterns that corresponded to the 15% dose margin using ArF immersion lithography. 3-dimensional grid defects were found to be the origin of the short defects. The half-pitch (hp) 15 nm L/S patterns were transferred successfully to SOG/spin-on-carbon (SOC) stacked substrate.

We also describe fabrication of sub-10 nm L/S patterns using a high-chi block copolymer (BCP).

Fibre Reinforced Polymer (FRP) is becoming a valid alternative to many traditional heavy metal industries because of its high specific stiffness over the more classical construction metals. Recent trend of more complex geometry of composites is causing increasing difficulty in composite manufacturing. A method to optimize the manufacturing process is thus imposed to ensure and improve the quality of manufactured parts. Because of the irregular 3D shapes of the composites, traditional flat sensor system is becoming unfavorable and nonpractical for monitoring purpose. In this work, the current development status of a deformable microsystem for in situ cure degree monitoring of a glass fibre reinforced plastic is presented. To accommodate the non-flat shape of the composites, the proposal is to interconnect non-deformable functional island, which contains the capacitive sensor for cure degree monitoring, with meander-shaped deformable interconnections. The developed sensor system is able to withstand the manufacturing process where change of pressure and internal strain, thus force exerted on the sensor system, is involved.

Density multiplication of patterned templates by directed self-assembly (DSA) of block copolymers (BCP) stands out as a promising alternative to overcome the limitation of conventional lithography. Using the 300mm pilot line available in LETI and Arkema’s materials, the main objective is to integrate DSA directly into the conventional CMOS lithography process in order to achieve high resolution and pattern density multiplication at a low cost. Thus we investigate the potential of DSA to address contact and via level patterning by performing either CD shrink or contact multiplication. Our approach is based on the graphoepitaxy of PS-b-PMMA block copolymers. Lithographic performances of block copolymers are evaluated both for contact shrink and contact doubling. Furthermore, advanced characterization technics are used to monitor in-film self-assembly process. These results show that DSA has a high potential to be integrated directly into the conventional CMOS lithography process in order to achieve high resolution contact holes.

Precise spatial patterns and micro and nanostructures of peptides and proteins have widespread applications in tissue engineering, bioelectronics, photonics, and therapeutics. Optical lithography using proteins provides a route to directly fabricate intricate, bio-friendly architectures rapidly and across a range of length scales. The unique mechanical strength, optical properties, biocompatibility and controllable degradation of biomaterials from silkworms offer several advantages in this paradigm. Here, we present the biochemical synthesis and applications of a “protein photoresist” synthesized from the silk proteins, fibroin and sericin. Using light-activated direct-write processes such as photolithography, we show how silk proteins can form high resolution, high fidelity structures in two and three dimensions. Protein features can be precisely patterned at sub-microscale resolution (µm) at the bench-top over macroscale areas (cm), easily and repeatedly with high-throughput. For instance, periodic, microstructured arrays can be patterned over large areas to form structurally induced iridescent patterns and functional opto-electronic structures. We further demonstrate how photocrosslinked protein micro-architectures can function for the spatial guidance of cells without use of cell-adhesive ligands as biocompatible and biodegradable scaffolds. The ease of biochemical functionalization, biocompatibility, as well as favorable mechanical properties and biodegradation of this silk biomaterial provide opportunities for otherwise inaccessible applications as sustainable, bioresorbable protein microdevices.

Over the last few years, significant improvements in sources, columns, detectors, control software, and accessories have enabled a wealth of new focused ion beam applications. In addition, modeling has provided many insights into ion-sample interactions and the resultant effects on the sample. With the knowledge gained, the community has found new ion-beam induced chemistries and ion-beam sources, allowing extending nanostructure fabrication and material deposition to smaller dimensions and better control for direct write and patterning. Insignificant proximity effects in resist-based ion beam lithography, combined with the availability of sub-nm ion spot sizes, opens the way to sub-10 nm structures and dense patterns. Additionally, direct-write ion beam nanomachining can process multilevel structures with arbitrary depths in one single process step, with all the information included in a single standard design file, thus enabling fabrication applications not achievable with any other technique.

As the conventional atomic force microscopy (AFM) uses a Cartesian coordinate system to scan sample and the probe has different characteristics in each direction, it is impossible to scan in arbitrary direction. Therefore, we present the AFM which is able to rotate its probe. The deflection of cantilever was measured using optical pickup head of DVD drive. For verifying the system feasibility, the multidirectional scanning of the standard sample was carried out. Also we presented the modified structure which includes aligner and mirror to enhance the performance.

To investigate template releasing process in nanoimprint lithography, template releasing energy (i.e. surface energy between the template and the resist polymer) in various releasing conditions is evaluated using multi-axial controlled releasing system. The releasing energy is in proportion to the surface free energy of the template, but does not depend on the velocity of releasing. Also, a peeling mode where the template is released from a single side and a lift-off mode where the template is removed in the perpendicular direction to the resist are examined. The result shows that the releasing energy by peeling mode is lower than that by lift-off modes.

Fabrication methodologies with high precision and tenability for nanostructures of metal and metal oxides are widely explored for engineering devices such as solar cells, sensors, non-volatile memories (NVM) etc. In this direction, metal and metal oxide nanopatterned arrays are the state-of-the-art platforms upon which the device structures are built where the tunable orderly arrangement of the nanostructures enhances the device performance. We describe here a coalition of fabrication protocols that employ block copolymer self-assembly and nanoimprint lithography (NIL) to obtain metal oxide nanopatterns with sub-100 nm spatial resolution. The protocols are easily scalable down to sub-50 nm and below.

Nanopatterned arrays of ZnO created by using NIL assisted templates through area selective atomic layer deposition (ALD) and radio frequency (RF) sputtering find application in NVM and photovoltaics. We have employed NIL that produced nanoporous polymer templates using Si molds derived from block copolymer lithography (BCL) for pattern transfer into ZnO. The resulting ZnO nanoarrays were highly dense (8.6 x 109 nanofeatures per cm2) exhibiting periodic feature to feature spacing and width that replicated the geometric attributes of the template. Such nanopatterns find application in NVM, where a change in the density and periodicity of the arrays influences the charge storage characteristics. The above assembly and patterning protocols were employed to fabricate metal-oxide-semiconductor (MOS) capacitor devices for investigating application in NVM. Patterned ZnO nanoarrays were used as charge storage centres for the MOS capacitor devices. Preliminary results upon investigating the flash memory performance showed good flat-band voltage hysteresis window at a relatively low operating voltage due to high charge trap density.

We investigated continuous fabrication of a large area 2-D metamaterial comprising a metal dot array on a dielectric coated substrate. We demonstrated patterning of metal dots arrays of varying patterns and shapes with diameter of about 2.5 μm and metal-to-metal spacing from 0.3 to 2.5 μm using a nano-imprinting stamp on a roller. The pattern was first fabricated on a standard photolithography mask, reproduced onto a silicon wafer master mold, and then transferred to a flexible polymer mold that was wrapped around a metal roller. The method was used to pattern a thin Al layer on top of SiO2 on a flexible polymer substrate. The aluminum was coated with a resist and the roller moved over the substrate with adjustable speed and pressure to imprint the fine pattern into the resist. The resist was cured, and a very thin layer of residual resist was removed by RIE, followed by a standard etching treatment for patterning the aluminum layer.

The as-etched pattern had very few defects and the optical properties of the metamaterial were excellent and correlated well with simulations. This work has shown that low cost, rapid roll-to-roll processing of 2-D metamaterial structures is possible.

The results obtained by direct nano-patterning demonstrate the potential of the SPM-based techniques that include surface scratching to create 3D nanostructures. Such techniques became known as tribo-nanolithography and have prospects of being successfully implemented in the future nanofabrication industry. An important obstacle to this, however, is the effect of wear at the nanometer scale which is critical to the stability of tribo-nanolithoraphic processes. Such stability is achievable via in-depth theoretical and experimental studies of friction at the nanoscale along with the development of pioneering equipment. Our work presents the results of experimental fabrication of nanostructures formed by nanoscratching with the use of the multifunctional scanning tunneling microscopy previously developed by the authors. The authors attempted scratching the silicon surface by using a boron-doped diamond tip. This operation was undertaken in the same direction sequentially with the tip sliding a side of the groove by one of the tip’s facets and the consequent surface scanning. Although not being applicable to non-conductive surfaces, the proposed technique has significant advantages. One advantage is related to the high stiffness of the tunneling probe as compared to the stiffness of the AFM cantilever. High stiffness and perpendicularity of the tip to the surface during surface processing eliminates bending beam effects on the typical AFM and ensures machining effectiveness. Purposely synthesized boron-doped single-crystal diamonds were used as a tip material. The results of experimental fabrication of nanostructures formed by nanoscratching with the use of the multifunctional scanning probe are demonstrated and discussed.

Although Helium Ion Microscopy (HIM) was introduced only a few years ago, many new application fields are budding. The connecting factor between these novel applications is the unique interaction of the primary helium ion beam with the sample material at and just below its surface. In particular, the HIM secondary electron (SE) signal stems from an area that is very well localized around the point of incidence of the primary beam. This makes the HIM well-suited for both high-resolution imaging as well as high resolution nanofabrication. Another advantage in nanofabrication is the low ion backscattering fraction, leading to a weak proximity effect. The lack of a quantitative materials analysis mode (like EDX in Scanning Electron Microscopy, SEM) and a relatively low beam current as compared to the SEM and the Gallium Focused Ion Beam are the present drawbacks of the HIM.

We report on Scanning Thermal Lithography (SThL), a recently introduced lithographic tool, for local thermochemistry on tert-butyl acrylate based polymer films featuring chemical cross links. The tailored polymer films afford platforms for controlled high molecular density coupling and surface immobilization of biologically relevant molecules, such as proteins. The thermally labile tert-butyl ester groups in tert-butyl acrylate based polymer films can be cleaved in air at temperatures above 150 °C to yield carboxylic acid functional groups for further (bio)- conjugation. The films were optimized to avoid plastic deformation at the elevated temperatures used during SThL. Exploiting these properties patterns with length scales as small as 35 ± 6 nm have been successfully thermally activated with SThL. Hence SThL comprises an attractive approach for the development of e.g. (bio)sensors and platforms for cell surface interaction studies with nanoscale patterns.

A novel rapid and easy-to-use method for patterning surfaces on large scale is described. Micro-patterns were created by direct contact of trypsin-functionalized poly(dimethylsiloxane) (PDMS) stamps with poly-L-lysine (PLL) layer adsorbed on silicon surface. The catalytic process does not involve ink transfer and thus lateral diffusion is avoided. As a result duplication of the stamp pattern is highly enhanced comparatively to standard microcontact printing procedure where PLL is used as ink and transferred on silicon surface. Patterning was revealed by fluorescence microscopy and atomic force microscopy (AFM). Adsorption on the patterned surfaces of cellulose nanocrystals was investigated as an example of application.

This study focused on the effect of UV irradiation on modification of polymethyl methacrylate-based photoresist, and then on wet photoresist (PR) removal of patterned structure (single damascene structure). Three single-wavelength UV sources were considered for PR treatment, with λ = 172, 222, and 283 nm. Modification of blanket PR was characterized using Fourier-transform infrared spectroscopy (FTIR; chemical change), spectroscopic ellipsometry (SE; thickness change), and dissolution in organic solvent (solubility change). While for patterned samples, scanning electron microscopy (SEM) was used for evaluation of cleaning efficiency. In comparison to 172 nm, the PR film irradiated by 222 nm and 283 nm photons resulted in formation of higher concentration in C=C bond. Immersion tests using pure N-methyl pyrrolidone (NMP) at 60 °C for 2 min showed that some improvement in PR removal was only observed for PR films treated by 283 nm UV for short irradiation times. Irradiation by photons at the other two wavelengths did not result in an enhancement of removal efficiency.

The PR film treated by 222 nm photons was chosen for further study with O3/H2O vapor at 90°C. Experimental results showed a complete PR and BARC removal for UV-treated PR, which can be explained by C=C bond cleavage by the oxidizer.

In this paper, we demonstrate a perfectly-ordered microbowl array with balanced dielectrophoresis (DEP) for a high-throughput single-cell analysis. In order to fabricate well-ordered microbowl array in a large area, we utilized three-dimensional diffuser lithography for photoresist mold and nickel electroplating technique for final microbowl structures on a silicon substrate. Single microbowl has six sharp apexes surrounding the microbowl perimeter. Each microbowl has a diameter of 10 μm, and a height of 9 μm, which can be controllable by patterns on mask and lithography conditions. To investigate feasibility for application to the microbowl array as a single-cell microarray, we used latex beads of 6.4 μm in an average diameter to be captured by dielectrophoretic force. The nickel microbowl array densely packed with a hexagonal geometry played as a bottom electrode, and an ITO-coated glass covered the nickel microbowl array as a top electrode while keeping a uniform gap between two electrodes. After injecting solution containing latex beads through the gap, we applied an AC signal (2 VPP, 1 MHz) between two electrodes to induce high electric field near the sharp apexes of the single microbowl. A negative DEP trap is formed at the center of the single microbowl with balanced DEP force from the six apexes. The experimental result shows that injected latex beads had been successfully and uniformly aligned and trapped at the microbowl array sustained by negative DEP.

Decisive advances in the fields of nanosciences and nanotechnologies are intimately related to the development of new instruments and of related writing schemes and methodologies. Therefore we have recently proposed exploitation of the nano-structuring potential of a highly Focused Ion Beam as a tool, to overcome intrinsic limitations of current nano-fabrication techniques and to allow innovative patterning schemes urgently needed in many nanoscience challenges. In this work, we will first detail a very high resolution FIB instrument we have developed specifically to meet these nano-fabrication requirements. Then we will introduce and illustrate some advanced FIB processing schemes. These patterning schemes are (i) Ultra thin membranes as an ideal template for FIB nanoprocessing. (ii) Local defect injection for magnetic thin film direct patterning. (iii) Functionalization of graphite substrates to prepare 2D-organized arrays of clusters. (iv) FIB engineering of the optical properties of microcavities.